At these contaminated sites, \u201c[a]s long as the subsurface is sufficiently aerated and\u00a0enough oxygen is present, methane oxidizing bacteria can degrade petroleum to CO2. Unfortunately, as these areas become inundated from sea level rise,\u00a0groundwater inundation or flooding,\u00a0the oxygen supply decreases, leading to enhanced production of methane,\u201d the memo states.<\/p>\n\n\n\n
Monitoring data from wells at Honolulu Harbor have shown that subsurface methane levels often spike during high tides and heavy rains.<\/p>\n\n\n\n
The memo notes that the concrete surfaces in the area and the installation of plastic liners at active fuel terminals have hampered oxygen circulation to the underground pollutants.<\/p>\n\n\n\n
\u201cMethane can build up in areas under pavement and move along utilities or\u00a0utility corridors, into confined spaces\u00a0and accumulate in other subterranean\u00a0pockets, creating a significant explosive\u00a0hazard for utility workers and construction crews,\u201d it states, adding that methane vapors appear to be \u201cenhanced during low atmospheric (barometric) pressures. This indicates a heightened risk of high methane concentrations during storm events.\u201d<\/p>\n\n\n\n
Felton says that the actual risk increased methane production poses is still being determined, since the gas would have to be concentrated and exposed to a spark to cause an explosion.<\/p>\n\n\n\n
In addition to methane, the memo also notes that sea water inundation of petroleum contaminated soil will likely\u00a0increase production of toxic, and flammable, hydrogen sulfide gas. <\/p>\n\n\n\n
\u201cHydrogen sulfide gas and methane vapors can migrate laterally and vertically and potentially intrude into buildings, creating indoor air quality\u00a0concerns and flammability\/explosive\u00a0hazards,\u201d it states.<\/p>\n\n\n\n
The memo, the content of which was shared at the Hawai\u2018i Climate Commission meeting last month, showed that there are about 100 HEER-regulated sites in and around Honolulu Harbor.<\/p>\n\n\n\n
Only about a dozen of them would fall directly within inundation areas if sea level were to rise 3.2 feet. But add a 100-year flood-type event on top of that, and all of the sites would be vulnerable.<\/p>\n\n\n\n Chemical Catastrophe<\/strong><\/p>\n\n\n\n As\u00a0Hakai\u00a0<\/em>magazine reported in an article published last November, the chemical contamination in certain parts of downtown Honolulu, combined with tidally\u00a0induced flooding, already put the public\u00a0drinking water supply at risk. If a corroded water main in Mapunapuna should break while submerged in polluted water during a high tide, hazardous chemicals could contaminate the pipeline and the drinking water it carries.<\/p>\n\n\n\n With sea level rise, that type of scenario will be an even greater, if not constant, threat.<\/p>\n\n\n\n The office found that more than 448 contaminated sites would be subject to inundation under a 3.2-foot rise in sea level: 307 sites on O\u2018ahu, 54 on Maui, 42 on Hawai\u2018i island, 23 on Moloka\u2018i, 21 on Kaua\u2018i, and one on Lana\u2018i.<\/p>\n\n\n\n \u201cWhen 1 percent annual-chance coastal flood zone and risk from rising groundwater or additional sea level rise up to six-feet is considered, the count of at-risk chemically contaminated sites rises dramatically,\u201d the memo states.<\/p>\n\n\n\n Before they started mapping which sites would be inundated under various scenarios, Felton says they had a fairly good idea that many of them would be impacted by sea level rise.<\/p>\n\n\n\n They were, however, surprised and concerned at the scope of sites vulnerable to extreme floods on top of a 3.2-foot rise in sea level.<\/p>\n\n\n\n \u201cWe know that the intensity and frequency of extreme floods is going to go up,\u201d she says.<\/p>\n\n\n\n The memo offers some examples of the kinds of public and environmental health threats these sites pose as sea level rises and extreme storm events become more frequent:<\/p>\n\n\n\n \u2022 Large sections of Honolulu\u2019s shoreline are underlain with fill composed, in\u00a0part, of lead-laden incinerator ash. This\u00a0includes Kaka\u2018ako Park and the land\u00a0extending several hundred yards inland. Thick caps of clean soil and pavement\u00a0cover the contaminated fill, but sea level\u00a0rise or storm surges \u201ccould disrupt the\u00a0caps and spread contaminated fill material along the shoreline and onto adjacent coral reefs,\u201d it states.<\/p>\n\n\n\n \u2022 Hilo\u2019s Wailoa River State Park was\u00a0the site of a Canec plant that produced arsenic-infused wallboard from bagasse\u00a0in the first half of the last century. Sediment in the park\u2019s Waikea Pond and the soil around it are heavily contaminated\u00a0with arsenic. Tsunamis in 1946 and 1960 further spread the arsenic into the\u00a0broader park area.<\/p>\n\n\n\n \u2022 The Wai\u2018anae High School Outdoor Air Rifle Range is located less\u00a0than one meter above sea level and the soil there is highly contaminated with lead.<\/p>\n\n\n\n \u2022 Decades ago, the Ke\u2018ehi Lagoon\u00a0Canoe Facility Increment II site in Honolulu Harbor was supposed to become a public park, with areas for race spectators and restored salt ponds for birds. Those plans were dropped after a 1994 site investigation discovered lead and polyaromatic hydrocarbons, which cause cancer, in the soil and groundwater. The department suspects the contamination came from a former asphalt plant in the area, as well as dumping of unclassified fill material into the\u00a0lagoon to create 10 acres of land. The low-elevation site is directly adjacent to the lagoon and receives stormwater run-off.<\/p>\n\n\n\n The Big Question<\/strong><\/p>\n\n\n\n So what, exactly can be done to prevent the contamination at these sites from migrating or creating explosive hazards?<\/p>\n\n\n\n \u201cThat\u2019s sort of the big question. Are we going to have to figure out a way to\u00a0remove all of this stuff? That\u2019s the tricky part,\u201d Felton says, adding that determining which sites pose a high risk to human health and the environment is key.<\/p>\n\n\n\n \u201cWe\u2019re really in the phase of raising awareness of this issue [that\u2019s] relatively unrecognized,\u201d Felton says.<\/p>\n\n\n\n The memo recommends that studies be done to \u201cexamine and measure changing contaminant conditions in high-risk areas and explore mitigation approaches to reduce methane risks and potential build-up of methane vapors.\u201d<\/p>\n\n\n\n It also recommends that criteria be developed to identify high-risk sites, with particular attention paid to \u201cformer dump sites and landfills, areas with extensive cover of contaminated fill\u00a0materials, current and former bulk fuel terminals and related pipeline networks with extensive petroleum contamination and other areas of contamination associated with past industrial activity.\u201d<\/p>\n\n\n\n In addition, it calls for developing guidance, policies, and regulations to address and mitigate adverse impacts and for identifying high risk sites for focused attention and resources to mitigate in a timely manner.<\/p>\n\n\n\n Once the high-risk sites are identified, mitigation options can be considered. \u201cIs it barriers to prevent the sea from coming in? Is it removal of that soil? Is it evacuation of the surrounding area? … There\u2019s not a ton of options,\u201d Felton says.<\/p>\n\n\n\n The removal of contaminated soil, which may have to be shipped to the mainland, is so expensive, it\u2019s a non-starter in a lot of cases, she says, adding that methods to clean soils in place are being developed.<\/p>\n\n\n\n \u201cWe\u2019re a long way from having the answer,\u201d she says.<\/p>\n\n\n\n \u2014 Teresa Dawson<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":" “It’s pretty intense,” says state toxicologist Dr. Diana Felton. With rising seas and more frequent severe storms expected as a result of the climate crisis, she and Department of Health colleague Dr. Iris van der Zander warn of the increased … Continued<\/a><\/p>\n","protected":false},"author":1,"featured_media":13765,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[486,11,341],"tags":[3],"class_list":["post-13782","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-august-2021","category-climate-change","category-pollution","tag-teresa-dawson"],"_links":{"self":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts\/13782","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13782"}],"version-history":[{"count":0,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/posts\/13782\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=\/wp\/v2\/media\/13765"}],"wp:attachment":[{"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13782"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13782"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/environment-hawaii.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13782"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/environment-hawaii.org\/wp-content\/uploads\/2021\/08\/Image-7-27-21-at-1.25-PM.jpg\")
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